Power supply device with two output voltages

ABSTRACT

The voltage supply device for the motor vehicle electrical system includes e.g. a self- or separately-excited generator having stator windings (10,11,12) and an excitation coil (E); a main bridge rectifier device connected to the stator windings having a first connector (B+) at which a first voltage (UB+) is delivered; an exciter bridge rectifier device connected to the stator windings; an exciter voltage regulator device connected between the exciter bridge rectifier device and the excitation coil (E) for regulation of an excitation current passing through the excitation coil; an additional rectifier device connected to the stator windings (10,11,12) having a second connector (B2+) at which a second voltage (UB2+) is tapped and a device for regulating a load current delivered by the generator to the first connector (B+) or the second connector (B2+) that includes a thyristor (Th0,Th4) connected to the first or second connector and a triggering device (A) whereby the generator has an optimal power output. During full load operation the load current is limited with the load current regulating device, while during partial load operation the exciter current is regulated by the exciter voltage regulator device. The invention can also be applied to voltage supply systems with permanently excited generators.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a device for voltage supply, in particular in amotor vehicle electrical system, and, more particularly, to a voltagesupply device in a motor vehicle electrical system comprising aself-excited, separately-excited or permanently-excited generatordelivering a load current and two rectifier arrangements connecteddownstream of the generator, which deliver a first voltage at a firstconnector and a second voltage at a second connector.

2. Prior Art

In connection with a motor vehicle electrical system, wherein the supplyvoltage required for the electrical consumers is generated by means of agenerator, it is known that more than one supply voltage should beprovided by the generator, so that a dependable, component-specificsupply voltage is assured. To this end it is proposed in DE-OS 37 41 242to embody a separately-excited rotary current generator in such a waythat, besides the usual rectified voltage of the vehicle electricalsystem, rotary current voltages are made available in addition, whichare directly used for supplying a window heater. In this case theregulation of the generator is performed with the aid of a voltageregulator which acts on the exciter current. The additional voltage forsupplying the heating coils is not rectified, so that losses whichunavoidably occur in the course of rectification are prevented.

With some vehicle electrical systems, permanently-excited generators areemployed in place of a separately-excited generator. Since an excitercurrent regulation is not possible with such generators, it is customaryto construct the bridge rectifiers downstream of the generator asregulated bridge/-half bridge rectifiers which, for example, comprisesemiconductor power switches which are regulated by an associatedvoltage regulator in such a way that the voltage supplied at the outputof the bridge rectifier is approximately constant or is not exceeded, sothat it can be used as the voltage of the vehicle electrical system andcan be used for charging the vehicle battery or batteries. Such apermanently-excited generator, including the associated regulated bridgerectifier, is known, for example, from DE-OS 38 41 610, however, thegeneration of a second voltage is not provided in this case.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improved voltagesupply device, in particular in a motor vehicle electrical system, whichhas two different connectors at which two different output voltages aredelivered from a generator and in which the generator operates in astate in which an optimum power output takes place.

According to the invention the voltage supply device includes

a self- or separately-excited generator having stator windings and anexcitation coil;

a main bridge rectifier device connected to the stator windings andhaving a first connector at which a first voltage is delivered by thegenerator;

an additional rectifier device connected to the stator windings andhaving a second connector at which a second voltage is tapped;

an exciter bridge rectifier device connected to the stator windings;

an exciter voltage regulator means connected between the exciter bridgerectifier device and the excitation coil for regulation of an excitationcurrent passing through the excitation coil; and

means for regulating a load current delivered by the generator to thefirst or second connector, so that the generator operates in anoperational state, in which an optimum power output takes place.

In the case in which a permanently excited generator is used in thevoltage supply device the voltage supply device comprises

the permanently-excited generator including its stator windings;

a main bridge rectifier device connected to the stator windings andhaving a first connector at which a first voltage is delivered by thegenerator;

an additional rectifier device connected to the stator windings andhaving a second connector at which a second voltage is tapped; and

means for regulating a load current delivered by the generator to thefirst or second connector, so that the generator operates in anoperational state, in which an optimum power output takes place.

In the case of both the self-excited generator and the permanentlyexcited generator the means for regulating the load current comprises athyristor connected to the first or second connector, which in apreferred embodiment is not included in either rectifier device, and atriggering device for triggering the thyristor, whereby during full loadoperation the thyristor is triggered by the triggering device so that alimitation of the load current takes place but during partial loadoperation the load current is controlled either by the exciter voltageregulator means or additional power components in the case of permanentexcitation.

The devices for voltage supply in accordance with the invention, havethe advantage of the known ones in that several voltages are availableand a regulation is simultaneously performed which, independently of theactually prevailing load, maintains the generator in an operationalstate in which an optimal power output can take place.

This advantage is achieved in that a generator with a second or severaloutputs is used, and further rectifier arrangements are inserted betweenthe generator stator and the additional connecting terminals, andadditional means are provided with the aid of which the load current ofthe generator can be acted on. In this case the additional meanscomprise controllable power switches which either replace a portion ofthe bridge rectifier or are connected downstream thereof. With aseparately-excited generator, the regulation of the exciter current caneither relate to the stator voltage, the B+ voltage or the B2+ voltageor Bx+ voltage, and is performed in the customary manner by the voltageregulator.

The mentioned advantages are achieved in the same way in connection witha permanently-excited generator wherein, in place of the exciter currentregulation, regulation can take place at all B+ connectors voltages/loadcurrents which can be tapped off.

It is particularly advantageous that it is possible by means of thedevices in accordance with the invention to perform a voltage regulationwhich assures that under full load operation of the generator a loadcurrent limitation takes place while, with a partial load operation ofthe generator the output voltage is performed either with the aid of thevoltage generator which regulates the exciter current or, with apermanently-excited generator, a voltage limitation takes place with theaid of additional power components.

Further advantages of the invention can be achieved by means of thesteps recited in the dependent claims.

If the stator winding of the generator, which consists of several turns,is tapped, it is possible in an advantageous manner to draw off voltagesin a fixed relationship with the regulated output voltage. It ispossible by means of such taps to construct a generator system forhigher voltages, in this case additional turns are necessary for thehigher voltages.

The invention can be employed in an advantageous manner for generatorswith star or delta connections, parallel multi-star or deltaconnections, or combinations of star and delta connections.

BRIEF DESCRIPTION OF THE DRAWING

Exemplary embodiments of the invention are represented in the drawingsand will be described in detail in the following description.

Shown in detail are in FIG. 1, a first exemplary embodiment, whereincustomary bridge rectifiers are employed, and an additional regulatedswitch element for limiting the load current of the generator ispresent.

An exemplary embodiment is represented in FIG. 2, wherein the positiverotary current bridge is replaced by controllable switch elements.

An exemplary embodiment is represented in FIG. 3, which largelycorresponds to that of FIG. 1, but in addition has a regulated output.

An exemplary embodiment is represented in FIG. 4, wherein each generatorwinding has two connections.

FIG. 5 shows an exemplary embodiment for an electrically excitedgenerator with single-phase load current regulation and FIG. 6 anexample with a permanently-excited generator corresponding to that ofFIG. 2, but which additionally has a regulated output.

FIGS. 7 to 9 show further exemplary embodiments of an electricallyexcited generator, wherein in FIG. 7 a star center tap with adownstream-connected additional diode and a load adjuster is present.

Examples for multi-taps with star and delta circuits are shown in FIGS.10 and 11.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Only the stator windings 10, 11, 12 of the generator G are representedin FIG. 1. In this case it is unimportant whether the generator G is aseparately-excited or a permanently-excited generator.

The stator windings 10, 11, 12 are connected in the customary mannerwith the bridge diode D. In the usual manner, the diodes D1, D2, D3 arecalled plus diodes, the diodes D4, D5, D6 minus diodes. The negativeconnection of the bridge diode D is identified by B-, the other side ofthe bridge diode D leads via a controllable semiconductor power switchD7 to the connection B+, where the voltage UB+ appears. Thesemiconductor power switch D7 is triggered by means of the triggeringdevice A.

FIG. 1 also shows an embodiment in which the power switch D7 is athyristor Th0. In this embodiment the current delivered at the connectorB+ is limited in the case of heavy or full load by means of thethyristor Th0 which is triggered by the triggering device A as explainedfurther below.

A further bridge diode with diodes D8, D9, D10 is connected with thestator windings 10, 11, 12 and with the centers of the bridge diodes Dand leads to the additional connector B+2, where the voltage UB2+appears.

By means of the circuit arrangement represented in FIG. 1, which islimited to the components essential for the invention, an additionalvoltage can be coupled out at the connector B+2 which, with theregulation still to be explained, has the desired properties. The loadcurrent IL delivered by the generator G is limited by the triggeringdevice A in such a way that in case of a heavy load indicatedsymbolically in FIG. 1 by the load resistor RL it is possible to limitthe current IL in a predetermined manner to be described later.

In the exemplary embodiment represented in FIG. 2, wherein like partsagain have the same identification, the positive semi-bridge of thebridge rectifier has been replaced by a triggered bridge rectifierwhich, for example, comprises the thyristors Th1, Th2, Th3, which aretriggered by the triggering device A for limiting the load current IL.

A further exemplary embodiment is represented in FIG. 3, which containsa permanently-excited generator (M) or, drawn in dashed lines, aself-exited or separately-excited generator, having an exciter coil E, aregulated additional output with a regulated voltage UB2+ and anexternal load switch or linear controller. Like components have againbeen given the same reference numerals, the same as in the furtherexemplary embodiments. In this exemplary embodiment of FIG. 3, whichrelates to a separately-excited generator, the exciter current bridgewith the exciter diodes D11, D12, D13 has been additionally represented.These exciter current diodes lead to the connector D+ and by means of itvia the voltage regulator SP and the exciter coil E to the generatorconnector B-. The current through the exciter coil IE is regulated in aknown manner by means of the voltage regulator SP, so that the outputvoltage of the generator remains approximately constant.

In the exemplary embodiment of FIG. 3, the transistor T1 is used forlimiting the load current and it can be triggered by means of thetriggering device A, with the aid of a further transistor T2 it ispossible to generate an additional regulated output voltage UB2+ on thecathode side of the additional diodes D8, D9, D10, wherein triggering ofthe transistor T2 takes place as a function of the load in such a way,that T2 operates as a linear regulator or switching regulator.

Incidentally, the transistor T2 can be omitted, if a self- orseparately-excited generator with exciter current regulation isemployed.

An exemplary embodiment is represented in FIG. 4, wherein the statorwindings 10, 11, 12 respectively have a second connector (which can alsobe provided several times), which are used for coupling out theadditional voltage via the diodes D8, D9, D10. This circuit arrangement,which again is suitable for a permanently-exited generator as long asthe transistor T2 is present, or for a self- or separately-excitedgenerator (in dashed lines) with exciter current regulation, wherein thetransistor T2 can be omitted, delivers a second voltage UB2+ as thesecond generator output voltage, which is higher than the voltage tappedat B+, wherein the size of the voltage depends on the tapping point.

The exemplary embodiments represented in FIGS. 5 to 6 differ from thosealready described only in that the one or several diodes are replaced bya thyristor. Here, the thyristors are identified by Th4 to Th7. It istherefore possible by means of the power components shown to represent1-, 2- or 3-phase-regulated semi- or full bridges. Additional outputscan be represented as 1-, 2- or 3-phase-regulated/unregulated semi- orfull bridges with differing power components. In addition, tapping atthe center by means of a regulated or unregulated rectifier is possible,as shown in FIG. 7 by way of example. The additional connector B2+ inFIG. 9 is connected with the generator via a bridge rectifier D15 to D20as well as a load current-limiting semiconductor component T2.

All exemplary embodiments represented in FIGS. 1 to 9 have at least onecomponent, which can be triggered, in the main bridge rectifier orbetween the generator and the connector B+, by means of which the loadcurrent IL of the generator can be acted on. Furthermore, all exemplaryembodiments have in common that, besides the customary connector B+, atwhich a first voltage UB+ can be tapped, at least one second connectorB2+ is provided, at which a second voltage UB2+ can be tapped wherein,depending on the design, this second voltage can be a d.c. voltage or ana.c. voltage. In addition, this second voltage can be equal to thecustomary voltage in the vehicle electrical system, or it can havehigher or lower values in respect to it, depending on the connection tothe stator windings 10, 11, 12 or the type of the power controller(linear or switch regulator).

With the exemplary embodiments with an additional bridge rectifier, thegenerator can deliver d.c. current at the additional outputs. Dependingon the connection of the additional output terminal or additional outputterminals, there can be a separation between the current supply systems,by means of an appropriate triggering of the controllable components,for example thyristors, it is possible to equip one of the outputs witha higher priority so that, for example, a charging priority for a startreservoir can be realized.

Circuits for a generator with multiple taps of the stator winding arerepresented in FIGS. 10 and 11, wherein FIG. 10 represents a starcircuit and FIG. 11 a multiple tap in a delta circuit. Several voltagescan be obtained by means of such circuits, the size of whose voltages isa function of the point of tapping, wherein ##EQU1##

If the initial voltage is regulated, the voltages UB2+, UB3+ which areobtained, are also regulated. By means of the employment of linearcontrollers, not shown in FIG. 10, FIG. 11, or the replacement of theindividual diodes by controllable semiconductor power switches, aregulation the same as in the exemplary embodiments 1 to 9 is possible.

Regulation of the generators takes place in such a way that with self-or separately-excited generators the output voltage at the terminal B+takes place by interrupting the exciter current, i.e. in the customaryway by means of a voltage regulator. However, when regulating agenerator, a differentiation is made between full load operation andpartial load operation. With full load operation, wherein the voltagesize of the generator is determined by the amount of the required loadcurrent, it might be possible that in case of too large a load theterminal voltage drops too low, so that problems arise for supplying theindividual consumers or that they must be designed in such a way thatthey still operate dependably even with clearly lower voltage in thevehicle electrical system. Therefore, in connection with the proposedregulation under full load operation, the load current IL of thegenerator is limited to a predetermined value, so that it is assuredthat the output voltage of the generator, and thus the additionaloutputs, cannot fall below a corresponding value. The limitation of theload current takes place by means of triggering of the controllablecomponent(s) of the bridge rectifier. In the exemplary embodimentsrepresented, the trigger device A will supply the thyristors withappropriate trigger signals.

With the exemplary embodiments, wherein the rotary current bridge wasnot partially, half or fully replaced by power switches, the loadcurrent limitation takes place by triggering the power switch betweenthe bridge rectifier and the connector B+.

The output voltage at the terminal B2+ can either be regulated with theaid of the transistor T2, or an unregulated voltage can be delivered.The transistor T2 can be omitted with a conventional exciter currentregulation and a regulated output voltage is still obtained.

During partial load operation of the generator, the output voltage iseither limited by the customary voltage regulator or, withpermanently-excited generators for example, is limited with the aid ofan (additional) power component disposed at the outputs. Triggering ofthe regulated rectifiers, the thyristors or semiconductor powercomponents, can take place in the form of a block, phase-shift operationor linear operation. A possibly provided d.c. current regulator can beoperated continuously.

By means of the different regulation of the generator in full loadoperation it is possible to operate the generator continuously in arange which just corresponds to the transition to full load. By means ofthis it is assured under all circumstances that the generator deliversthe maximally possible power output, which is obtained at the partialload/full load threshold.

Determination of the load on the generator can take place by measurementof its output voltage, by measurement of the load current or of theexciter current/keying ratio, etc.

The invention is not limited to the exemplary embodiments represented,instead it can basically also be realized for generators which not onlyhave one or two, but a plurality of additional outputs, for example bymeans of additional winding taps or parallel or insulated additionalwindings wherein, depending on the tap point, it is possible to setdifferent voltage sizes at the corresponding outputs Bx+, so thatcomponent-specific voltages UBx+ can be obtained, where x=1, 2, 3, etc.

Other high-speed components can also be employed instead of thethyristors represented, for example high-speed semiconductor components,it is also possible for a bridge to have different circuit elements.

The bridge rectifiers can be designed as semi-regulated bridges withdiodes or Zener diodes, or as fully regulated bridges, which assuretotal junction protection.

With permanently-excited generators, each connection must be providedwith a power controller, so that no excess voltage can appear at theconnectors. In addition to the voltage limiting function, these powercontrollers can also be used for load current regulation to the mosteffective generator point.

The regulation of generators of the following types or in combination ofthe following characteristics can be:

    ______________________________________                                        Stator winding:                                                                            Star or delta, or combination singly or                                       multiply (parallel or insulated from each                                     other)                                                           Excitation:  Self, separately, permanently or combined                        Taps:        Center of the diode or power switch, or                                       combination                                                                   Winding taps singly or multiply                                  Rectifiers:  Rotary bridge, singly                                                         Rotary bridge, multiply                                          additional:  Common ground reference or                                                    different ground reference                                       type:        Semi-regulated rotary bridge                                                  fully-regulated rotary bridge                                                 partially-regulated rotary bridge (only 1                                     or 2 phase)                                                      Diodes:      Standard diodes,                                                              Schottky or low voltage diodes                                                Z-diodes                                                         Controllable Plus- or minus-sided                                             Power Switches:                                                                            at one or several or all connectors                              ______________________________________                                    

In connection with generators with star circuits with additional turnsat the outer winding ends, windings with lower power cross section canalso be used for utilizing the free spaces in the winding chamber.

In connection with generators with separate stator winding(s), windingswith star or delta points which are insulated from each other, oruninsulated star points are placed into the winding chambers. Here,combinations of star and delta circuits are also conceivable.

What is claimed is:
 1. A device for voltage supply in a motor vehicleelectrical system comprisinga self- or separately-excited generator (G)having stator windings (10,11,12) and an excitation coil (E); a mainbridge rectifier device connected to said stator windings (10,11,12),said main bridge rectifier device having a first connector (B+) at whicha first voltage (UB+) is delivered by said generator; an additionalrectifier device connected to said stator windings (10,11,12), saidadditional rectifier device having a second connector (B2+) at which asecond voltage (UB2+) is tapped; an exciter bridge rectifier deviceconnected to said stator windings, said exciter bridge rectifier devicehaving a exciter bridge rectifier connector (D+); exciter voltageregulator means (SP) connected between said exciter bridge rectifierdevice and said excitation coil (E) for regulation of an excitationcurrent passing through the excitation coil; and means(T1,T2,Th0,Th1,Th2,Th3; A) for regulating a load current (IL) deliveredby said generator to said first connector (B+) or said second connector(B2+), so that said generator operates in an operational state, in whichan optimum power output takes place; wherein the means for regulatingsaid load current comprises a thyristor (Th0), said thyristor (Th0)being connected to said first connector (B+) or said second connector(B2+) and not included in any of said rectifier devices, and atriggering device (A) for triggering said thyristor (Th0), wherebyduring full load operation said thyristor is triggered by saidtriggering device (A) so that a limitation of said load current takesplace, during partial load operation an output voltage of the generatoris regulated by means of said exciter voltage regulator means (SP) andsaid full load operation is recognized when said output voltage of saidgenerator falls below a predetermined value.
 2. The device as defined inclaim 1, wherein said stator windings (10,11,12) have a commonconnection point connected with said first connector (B+) and saidsecond connector (B2+) of said rectifier devices.
 3. The device asdefined in claim 1, wherein said stator windings (10,11,12) areconnected in a star point circuit having a star point.
 4. The device asdefined in claim 1, wherein said stator windings (10,11,12) have aplurality of taps connected to additional connectors (Bx+) at whichadditional voltages (Ubx+) are tapped and respective magnitudes of saidadditional voltages depend on a location of said taps in said statorwindings.
 5. The device as defined in claim 1, wherein said statorwindings (10,11,12) are connected in a delta circuit.
 6. A device forvoltage supply in a motor vehicle electrical system comprisingapermanently-excited generator (M) including stator windings (10,11,12);a main bridge rectifier device connected to said stator windings(10,11,12), said main bridge rectifier device having a first connector(B+) at which a first voltage (UB+) is delivered by said generator; anadditional rectifier device connected to said stator windings(10,11,12), said additional rectifier device having a second connector(B2+) at which a second voltage (UB2+) is tapped; and means(T1,T2,Th0,Th1,Th2,Th3; A) for regulating a load current delivered tosaid first connector (B+) or said second connector (B2+) by saidgenerator, so that the generator operates in an operational state, inwhich an optimal power output takes place; wherein the means forregulating said load current comprises a thyristor (Th0), said thyristor(Th0) being connected to said first connector (B+) or said secondconnector (B2+) and not included in either of said rectifier devices,and a triggering device (A) for triggering the thyristor (Th0), wherebyduring full load operation said thyristor is triggered by saidtriggering device (A) so that a limitation of said load current takesplace, during partial load operation an output voltage of the generatoris regulated by means of additional power components and said full loadoperation is recognized when said output voltage of said generator fallsbelow a predetermined value.
 7. The device as defined in claim 6,wherein said stator windings (10,11,12) have a common connection pointconnected with said first connector (B+) and said second connector (B2+)of said rectifier devices.
 8. The device as defined in claim 6, whereinsaid stator windings (10,11,12) are connected in a star point circuithaving a star point.
 9. The device as defined in claim 6, wherein saidstator windings (10,11,12) have a plurality of taps connected toadditional connectors (Bx+) at which additional voltages (Ubx+) aretapped and respective magnitudes of said additional voltages depend on alocation of said taps in said stator windings.
 10. The device as definedin claim 6, wherein said stator windings (10,11,12) are connected in adelta circuit.
 11. A device for voltage supply in a motor vehicleelectrical system comprisinga self- or separately-excited generator (G)having stator windings (10,11,12) and an excitation coil (E); a mainbridge rectifier device connected to said stator windings (10,11,12),said main bridge rectifier device having a first connector (B+) at whicha first voltage (UB+) is delivered by said generator; an additionalrectifier device connected to said stator windings (10,11,12), saidadditional rectifier device having a second connector (B2+) at which asecond voltage (UB2+) is tapped; an exciter bridge rectifier deviceconnected to said stator windings, said exciter bridge rectifier devicehaving a exciter bridge rectifier connector (D+); exciter voltageregulator means (SP) connected between said exciter bridge rectifierdevice and said excitation coil (E) for regulation of an excitationcurrent passing through the excitation coil; and means (T1,T2,Th0; A)for regulating a load current (IL) delivered by said generator to saidfirst connector (B+) or said second connector (B2+), so that saidgenerator operates in an operational state, in which an optimum poweroutput takes place; wherein the means for regulating said load currentcomprises a thyristor (Th4), said thyristor (Th4) being connected tosaid first connector (B+) or said second connector (B2+) and included insaid main rectifier device, and a triggering device (A) for triggeringsaid thyristor (Th4), whereby during full load operation said thyristoris triggered by said triggering device (A) so that a limitation of saidload current takes place, during partial load operation an outputvoltage of the generator is regulated by means of said exciter voltageregulator means (SP) and said full load operation is recognized whensaid output voltage of said generator falls below a predetermined value.